When pressed, the material between nearby metal droplets cracked, allowing the metal to flow between gaps. After the pressure was removed, metal remained in the cracks. This created the pathway through which electricity could flow, using the unique flexibility built into the material itself.
“We were able to watch the process happen in two dimensions and then reconstruct the pathways in three dimensions,” Zu said. “That gave us a much clearer picture of how local cracks and liquid transport build into a larger conductive network.”
The team also developed a mathematical model that predicts how much force is needed to make the material conductive. This prediction worked for many designs, from millimeter-sized droplets to droplets only a few dozen micrometers wide.
“By carefully observing what was going on during experiments, we could connect pathway formation to a fracture mechanics model,” author Grennan said. “Now we can design liquid metal composites that activate at necessary forces and length scales for particular applications.”
Where can liquid metals be used?
This work provides a new framework for designing how and when liquid metal composites become conductive, which could help manufacturers control where conductivity forms in stretchable sensors, wearable electronics, and soft robots.
“Knowing what governs how conductive networks form, we can use that knowledge to guide materials design and manufacturing,” Bartlett said. “That opens the door to manufacturing soft electronic systems where conductivity is programmed in through the material architecture and the way the device is processed.”
DOI: 10.1016/j.matt.2026.103089